Means for grinding automotive brake shoes



Nov. 22, 1960 H. B. BARRETT ,960,8 7

MEANS FOR GRINDING AUTOMOTIVE BRAKE SHOES Filed Dec. 12 1956 2 Sheets-Sheet 1 INVENTOR. HARRY B. BARRETT ATTORNEY Nov. 22, 1960 Filed Dec. 12, 1956 FIG-8 H. B. BARRETT MEANS FOR GRINDING AUTOMOTIVE BRAKE SHOES III, IIIIA W 2 Sheets-Sheet 2 INVENTOR.

BARRETT HARRY B.

ATTORNEY MEANS FOR GRINDING AUTOMOTIVE BRAKE SHOES Harry B. Barrett, Clayton, Mo. (2101 Cass Ave. St. Louis, Mo.)

Filed Dec. 12, 1956, Ser. No. 627,895

13 Claims. (Cl. 51-241) This invention relates to certain new and useful improvements in means for grinding automotive brake shoes and is a continuation in part of my co-pending application Serial No. 551,840, filed December 8, 1955, now Patent No. 2,822,650.

Automotive brakes have created a serious brake servicing problem. As is well known, automatic automotive transmissions impose severe wear and tear 'on automotive brake systems and such transmissions are now very generally used even in the so-calledlow-priced car field. Consequently, more frequent servicing and repair of automotive bra'kes becomes necessary. Furthermore, present day types of brake systems require concentric grinding while theshoes are mounted in operating position on the backing plate, inasmuch as such procedure becomes the only practical method of shoe centralization. However, the current wide-spread adoption and use of 'full floating shoes makes such brake shoe grinding very difficult 'for the reason that both brake shoes are aligned on a com mon pivot point called "the shoe anchor and are attached at the oppositeends with an expanding adjuster for wear. The shoes tend to shift diametrally as a unit when grind ing or adjusting pressure is applied to either single shoe.

It is, therefore, the primary object of thepresent invention to provide means for concentrically grinding automotive brake shoes of the full floating type while the latter are mounted in operative position upon the backing plate of the brake.

It is a further object of the present invention to provide means for stabilizing 'or holding the brake shoe assembly of full floating shoes, while one shoe is being ground so that the shoe being ground will be properly positioned and will thereby be ground to a proper concentric are. It is another object-of the present invention to provide means for grinding automotive brake shoes of the full floating type so that the braking surfaces of such shoes are precisely concentric quickly, simply, and conveniently, and in a manner which can be employed by the average automotive mechanic with very simple training or instruction.

With the above and other objects in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the-claims.

In the accompanying drawings (three sheets)- Fig. 1 is a diagrammatic view of an automotive brake having so-called full floating shoes;

Fig. 2 is a perspective view of an automobile brake assembly showing the installation thereon of a brake shoe grinder, said grinder being shown on the front spindle of an automobile, constructed in accordance with and embodying the present invention;

Fig. 3 is a perspective view of the brake shoe positioner forming a part of the present invention;

Figs. 4 and 5 are side elevational views of the brake shoe positioner as respectively applied to two different types of backing plates currently in use; Fig. 6 is a front elevational view of a brake assembly atent carrying out such method.

2,9663%7 Patented 'Nov. 22, 1960 Fig. 9 is a fragmentary sectional view taken along line 9-9 of Fig. 8; and

Fig. '10 he perspective view of the locking post forming a part of the brake shoe vpositioner shown in Figs. 6 to 9, inclusive.

In order to understand the present invention, it perhaps should be pointed out that an automotive brake having so-called full floating brake shoes is a brake which comprises a backing plate b, as shown in Fig. 1, and two arcuate brake shoes s mounted thereon in such a manner that the shoes .s will shift as a unit in a diametral or crosswise direction as indicated by the ar row depending uponthe direction in which external force is applied. The specific construction of such automotive brakes, however, is conventional and, therefore, need not be described in particular detail herein. The present invention, broadly speaking, resides in providing a simple and effective method for servicing such brakes by holding one shoe stationary and thereby locating the other shoe in proper position so that its braking surface can be concentrically ground. Such other shoe is then concentrically ground by a grinding tooloperatively mounted on the axle spindle or axle. Thereupon, the ground shoe is held stationary so as to position the first shoe and the braking surface of that shoe similarly ground in turn. The present invention also includes the provision of novel shoe positioning and shoe grinding means for Referring now in more detail and by reference characters to the drawings, which illustrate practical embodi ments of the present invention, A designates a brake shoe grinder somewhat similar to that brake shoe grinder described in the abovementioned co-pending application, and comprising a spindle-mounted bracket 1 integrally including a sleeve 2, an abutment plate 3, and a shoulder plate 4 connected by a reinforcing web 5. The abutment plate 3 and shoulder plate 4 are respectively provided with precisely machined outwardly "presented contact faces 6, 7, which are relatively perpendicular. Furthermore, the contact face 7 is parallel to the longitudinal axis of the sleeve 2, the latter being provided at one end with a tapered counter-bore 8, which is adapted to receive either a conventional wheel bearing or a conical adapter 9, by which the sleeve 2 can be fitted upon a conventional tapered front axle spindle r.

The abutment plate 3 is preferably somewhat triangular in peripheral contour and is provided with three apertures 10, 11, 12, all of which are located at equal radial distances outwardly from the longitudinal center line of the sleeve 2 and are sized for snug-fitting, but slidable, disposition over the axle mounting studs of an automobile rear wheel, the latter being conventional and, hence, not being shown.

.Operatively mounted on and extending outwardly from the shoulder plate 4, for rotation with respect thereto, is an integrally formed collar 16 which supports a radially outwardly projecting frame 17 integrally including an offset arm 18. The collar 16 is'drilled and tapped to receive a retainer screw 23. 'Removably mounted upon the offset arm 18 is a filter-canister 24 having a perforated side wall 25 and perforated end wall 26. The canister '24 is filled with a suitable filter medium which is conventional and is, therefore, not shown ordescribed herein. Formed integrally with and extending upwardly from the frame 17 is a motor-supporting bracket 28 including a mounting pad 29 and handle-grip 30.

Bolted or otherwise rigidly secured upon the mounting pad 29 is an electric grinder 32 having a conventional electrical connector cord 33, switch 34 and a disk-shaped grinder plate 36 having an abrasive disk 37 adhesively or otherwise suitably secured to its exposed face.

It will be noted that the axis of the grinder plate 36 is parallel to, but laterally offset from, the axis of the collar 16. Furthermore, the collar 16 is rotatable upon the post 13 when the retainer screw 21 is disengaged from the groove 14.

Provided for use in practicing the method of the present invention is a somewhat L-shaped shoe positioning clamp B comprising a side leg 38 and a top leg 39, the latter being integrally provided at its outer end with an extension 40 and an inwardly turned hook-flange 41. Threadedly mounted in, and extending through the lower end of the side leg 38 is an adjustment screw 42 having a knurled knob 43 at its outer end and a rounded-off contact face 44 on its inner end. Similarly mounted in the side leg 38 is an adjustment screw 45 having a knurled knob 46 at its outer end and a blunt contact face 47 at its inner end. Also threadedly mounted in, and extend ing through, the extension 40 is an adjustment screw 48 having a knurled knob 49 at its outer end and a blunt contact face 50 at its inner end. Mounted encirclingly around the adjustment screw 48 between the knob 49 and the extension 40 is a spring 51. The side leg 38 is also provided with an internally threaded alternate aperture 52 into which the adjustment screw 45 can also be optionally inserted.

The shoe positioning clamp B is fastened upon the backing plate b and clamped upon the peripheral flange fthereof, substantially as shown in Fig. 4, and the screw 48 adjusted to bear against the brake shoe .9 and hold it stationary in a selected position so that the opposite shoe .9 is also positioned in precise relation to the center line of the brake assembly and can be accurately ground. In the case of a brake of somewhat different design wherein the backing plate b' does not have a peripheral flange f, the adjustment screw 45 can be inserted in the alternate aperture 52 and the clamp B thereby firmly attached as shown in Fig. 5.

In use, the brake shoe grinder A may be mounted upon the axle spindles of a front wheel assembly, substantially in the manner shown in Fig. 2, in which case the frame 17 will be positioned in relation to the mounting bracket 1, so that the abutment plate 3 will be faced outwardly, as shown, and the set screw or retainer screw 21 may then be tightened down so that the frame 17 will be locked securely in such position.

Similarly, the grinder A may be mounted on a rear axle assembly substantially in the manner shown and described in detail in connection with the somewhat similar brake shoe grinder forming the subject-matter of my copending application abovementioned.

Thereupon, the electrical connector cord 33 can be plugged into any conventional source of electrical current and the switch 34 closed to energize the grinder and rotate the grinder plate 36. With the grinder plate 36 rotating, the frame 17 is swung to-and-fro in a circumferential arc to grind a truly concentric surface upon the braking surfaces of the brake shoes.

After the shoe s has been properly ground, the shoe positioning clamp B is removed and remounted to hold the shoe s and leave the shoe s in position to be ground. When this adjustment has been made, the shoe s may be ground in the same manner and precisely to the same concentric arc. Finally, the positioning clamp B is removed and the brake reassembled for use. In this connection it should be noted that the positioning clamp B is of such size and shape thatthe drum cannot be reinstalled until the clamp is removed thereby making it impossible for the mechanic to inadvertently leave the clamp in the brake assembly.

There is another type of automotive brake assembly of the type shown in Figs. 6 and 7 which is widely in use on automobiles manufactured by Chrysler Corporation and its afiiliates, and such brake assemblies employ an intermediate plate p which is provided with elongated or oval-shaped apertures 0. For use with such brake assemblies, a modified form of clamp B is provided, comprising a short rod 53 having a handle member 54 extending diametrally through its outer end. At its other end, the rod 53 is integrally provided with a diametrally enlarged annular flange 55 and a diametrally reduced neck 56 sized to fit loosely within the aperture 0. At its outer end the neck 56 is provided with a diametral- 1y disposed cross-bar 57 also sized to pass through the aperture 0 when properly aligned therewith. Extending diametrally through the rod 53 a short distance outwardly with respect to the flange 55 is a pin 58 which may be soldered, shrunk, or otherwise tightly fitted in place and loosely disposed on the rod 53 between the pin 58 and the flange 55 are two matching internested spring leaves 59, 59', comprising diametrally extending central grooves 60, 60', bordered by parallel ridges 61, 61', and 62, 62, respectively. At their outer ends the springleaves 59, 59', are curled up in the provision of endflanges 63, 63, and 64, 64', respectively, the latter being centrally bifurcated as at 65, 65', and struck down in the provision of positioning ears 66, 66'. Normally, the rod 53 is turned so that the pin 58 lies in the groove 60 and the spring-leaves 59, 59', are loose. In this position, also, the cross-bar 57 can be readily inserted through the aperture 0. Thereupon, the spring-leaves 59, 59', can be positioned in the shoe-straddling position shown in Figs. 6 and 7, with the cars 66, 66', located in an available auxiliary aperture 0'. Then the rod 53 is pressed inwardly flexing the spring-leaves 59, 59', until the neck 56 extends through the aperture 0, whereupon the rod 53 is turned to rotate the cross-bar 57 into the position shown in Fig. 9, thereby locking the clamp B securely in place and clamping the brake shoe nonshiftably in place for grinding in the manner heretofore described. The clamp B also is of such size and shape that it must be removed before the brake can be reassembled and, therefore, cannot be accidentally left in the brake assembl It should be understood that changes and modifications in the means hereinabove set forth may be made and substituted for those herein specifically shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said automotive brakes shoes are operatively mounted upon a backing plate, said fixture including clamping means for engagement with the backing plate, first positioning means for locating said fixture in fixed relation to said backing plate, an arm projecting outwardly and over the rim of the backing plate and laterally beyond the face of the backing plate in radially spaced overlying relation to the brake shoe, and second positioning means adjustably mounted in said arm in parallel relation to the backing plate for holding the brake shoe in fixed relation to the backing plate.

2. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said automotive brake shoes are operatively mounted upon a backing plate, said fixture including clamping means for engagement with the backing plate, first positioning means for locating said fixture in fixed relation to said backing plate, an arm projecting outwardly and over the rim of the backing plate and laterally beyond the face of the backing plate in radially spaced overlying relation to the brake shoe, and second positioning means operatively mounted in said arm in parallel relation to the backing plate for holding the brake shoe in fixed relation to the backing plate.

3. A shoe positioning :fixture adapted for use in conjunction with the grinding of automotive brake shoes while said automotive brake shoes are operatively mounted upon a backing plate, said fixture including clamping means for engagement with the backing plate, first positioning means for locating said fixture in fixed relation to said backing plate, an arm projecting outwardly and over the rim of the backing plate and laterally beyond the face of the backing plate in radially spaced overlying relation to .thebrake shoe, and spring-biased second positioning means :operatively mounted in said arm in parallel relation to the brakng plate for :holding the brake shoe in fixed relation to the backing plate.

4. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said automotive brake shoes are in operative position with'respect to an intermediate plate therein, said fixture comprising a rod, means on one end of said rod for removable interlocking engagement with the intermediate plate, spring means mountable on said rod, and means on said rod for releasably urging said spring means into gripforming engagement with a brake shoe so as to rigidly clamp the shoe against the intermediate plate.

5. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said automotive brake shoes are in operative position with respect to an intermediate plate therein, said fixture comprising a rod, means on one end of said rod for removable interlocking engagement with the intermediate plate, leaf-spring means mountab e on said rod and extending substantially radially outwardly therefrom, and means on said rod for releasably urging sa d leaf-spring means into grip-forming engagement with a brake shoe so as to rigidly clamp the shoe against the intermediate plate.

6. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said brake s oes are onerativelv mounted upon a backing plate, said fixture including a body portion having a leg and an arm. said arm projecting outwardly over the rim of the backing plate in radially spaced overlying relation to the brake shoe. said arm and leg having cooperating means for clamping engagement with the backing plate, and positioning means threadedly mounted 011 said arm for movement along a line parallel to a radius of said back ng plate whereby to move said brake shoe into he d position with respect to said backing plate.

7. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said brake shoes are operatively mounted upon a backing plate, said fixture including a body portion having a leg and an arm, said arm projecting outwardly over the rim of the backing plate in radially spaced overlying relation to the brake shoe, a flange depending from said arm and adapted to engage one face of the backing plate, means mounted in the leg and adapted to engage the other side of said backing p ate so that said means and flange cooperate to clamp said fixture to the backing plate, and positioning means threadedly mounted on said arm in lateral displacement from said backing plate for locating the brake shoe with respect to said backing plate.

8. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said brake shoes are operatively mounted upon a backing plate, said fixture including a body portion having a leg and an arm, said arm projecting outwardly over the rim of the backing plate in radially spaced overlying relation to the brake shoe, a flange depending from said arm and adapted to engage one face of the backing plate, a plurality of members threadedly mounted in the leg for engagement with the other side of said backing plate so that said threaded members and flange cooperate to clamp said fixture to the backing plate, and a springbiased member operatively mounted in said arm in lateral displacement from said backing plate and parallel to a radius of said backing plate for holding the brake shoe with respect to the backing plate.

9. A shoe positioning fixture for use in conjunction with the grinding of brake shoes while said shoes are in the operative position, said fixture including means for determining shoe position with respect to a reference plate, means for locking the shoe in the desired position with respect to the reference plate, and means for looking said fixture to said reference plate when the shoe is locked in the desired position.

10. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said shoes are operatively mounted on a backing plate, said fixture comprising a body portion having a first rod-like member threadedly mounted therein, a first arm portion extending outwardly from said body portion in a substantially perpendicular direction and having a second rod-like member threadedly mounted near its end, said first arm portion having a downwardly looking flat face for abutment with'the edge of said backing plate, a second arm portion intermediate said second rod-like member and said body portion and extending downwardly substantially perpendicular to said first arm portion, said downward extension being elongated and being terminated by an inward bend to form a third arm portion which is elongated and extends inwardly substantially parallel to said first arm portion, said third arm portion being endwise terminated with a flat face for abutment with the face of said backing plate, a first leg portion extending inwardly and downwardly from said body por tion at an obtuse angle, said first leg portion being elongated, a second leg portion extending downwardly in a direction substantially parallel to said body portion, said second leg portion being elongated and having a third rod-like member threadedly mounted therein; said first rod-like member having a surface for urging said backing plate into clamped abutment with the fiat face of said third arm portion, said second rod-like member having a flat face for facewise contact with said backing plate after said backing plate has been brought into clamped abutment with the flat faces of said first arm portion and said third arm portion; said third rod-like member having a downwardly presented face for engagement with said brake shoe whereby to secure said brake shoe in the proper grinding position.

11. A shoe positioning fixture adapted for use inconjunction with the grinding of automotive brake shoes while said shoes are operatively mounted on a backing plate having a flange extending away from said plate towards said shoe, said fixture comprising a body portion, a first arm portion extending outwardly from said body portion in a substantially perpendicular direction and having a first rod-like member threadedly mounted near its end, and a second rod-like member threadedly mounted intermediate the first rod-like member and said body, a second arm portion intermediate the first and second rod-like members and extending downwardly substantially perpendicular to said first arm portion, said downward extension being elongated and being terminated by an inward bend to form a third arm portion which is elongated and extends inwardly substantially parallel to said first arm portion, said third arm portion being endwise terminated with a flat face for abutment with the face of said backing plate and having an upwardly presented face for abutment with the lower face of said flange of said backing plate, a first leg portion extending inwardly and downwardly from said body portion at an obtuse angle, said first leg portion being elongated, a second leg portion extending downwardly in a direction substantially parallel to said body portion, said second leg portion being elongated and having a third rod-like member threadedly mounted therein, said second rod-like member having a downwardly presented face whereby nee e to urge the inner face of the flange on the backing plate into facewise abutment with the upwardly presented face of said third arm portion, said third rod-like member having a flat face for facewise contact with said backing plate whereby in cooperation with said second rod-like member to bring said backing plate into clamping abutment with the fiat faces of said third arm portion; and said first rod-like member having a downwardly presented face for engagement with said brake shoe whereby to urge said brake shoe in the proper grinding position.

12. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said shoes are in the operative position, said fixture comprising an intermediate plate having an elliptical slot, a rod of substantially constant diametral size terminated at one of its ends by an elliptically shaped member, said elliptically shaped member being of slightly smaller size than the elliptically shaped slot in said intermediate plate and connected to said rod by a first elongated member of substantially smaller size than the minor axis of said elliptical member, a second elongated member extending intermediate from said rod, said second member being mutually perpendicular to both the axis of said rod and the major axis of said elliptical member, spring means containing a hole through which the rod is inserted and having a recess in which said second member rests when said shoe positioning fixture is in the unlocked position, said spring means being for disposition between said second member and said elliptically shaped member on said rod and extending outwardly away from said common axis of said rod and first cylindrical element at an obtuse angle, said spring means having a pair of surfaces for engagement of said brake shoe, and handle means attached to said rod whereby, when said intermediate plate is disposed behind said brake shoe, said rod can be urged towards said brake shoe and rotated, thereby causing said elliptical member to pass through said elliptical slot and rotate therein into lock-forming engagement, whereby said shoe is secured in position between said spring means and said intermediate plate. 13. A shoe positioning fixture adapted for use in conjunction with the grinding of automotive brake shoes while said automotive brake shoesare operatively mounted upon a backing plate, said fixture including an adjustably mounted element positioned for engagement with the backing plate and, when so engaged, extending outwardly in substantially perpendicular relation to the backing plate, and auxiliary means extending parallel with, and in outwardly spaced relationto, the backing plate, said auxiliary means being provided at its outer end with a clamping element adapted to engage the one brake shoe and hold it in stationary position with relation to the backing plate.

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